My problem begins when I had to add a single landing page to an existing Drupal website. I've never worked with this CMS, so I just created a folder for this page in the root folder and put all the content there.
Then it appeared that I need to send mail from this page after submitting a form there. As I understood I can't use drupal_mail() function there, so I tried something like that:
$to = $email;
$subject = 'the subject';
$message = 'hello';
$headers = 'From: ' . $email . "
" .
'Reply-To: ' . $email . "
" .
'X-Mailer: PHP/' . phpversion();
mail($to, $subject, $message, $headers);
But that gave me no result.
Then I installed SMTP auth module for Drupal and tried to send mail, but again I had no result. However, test messages from SMTP module have been sent correctly.